vboxusers group should be added as a system group, not as an ordinary group

Description

When installing VirtualBox-2.2.0_45846_fedora9-1.i386.rpm (on Fedora 10) a vboxusers group is created. Unfortunately it is created as an ordinary group and not as a system group, which means that it can clash with other (older) groups which haven't been (re)added yet to /etc/group.

The problem can be fixed by running groupadd with the -r parameter. Quoting from the man page:

-r This flag instructs groupadd to add a system account. The first available gid lower than 500 will be automatically selected unless the -g option is also given on the command line. This is an option added by Red Hat.